1. Field of the Invention
The invention pertains to a concise air diffuser system particularly suitable for use with medical thermal blankets wherein the temperature of forced air is controlled by passing the air over a heat exchanger.
2. Description of the Related Art
In the assignee's U.S. Pat. No. 5,125,238 and the assignee's U.S. Pat. No. 5,300,098, a medical thermal blanket, and controls, are disclosed wherein temperature controlled air, usually heated air, is forced into an inflatable blanket having a plurality of orifices whereby the heated air impinges upon a patient to maintain or increase body temperature. Such blankets are often used in post surgery and trauma situations.
Because of the nature of a medical thermal blanket, i.e. the apparatus must be of concise configuration as to be readily portable as placed bedside, the space available for heating the air prior to introduction into the blanket is limited, and it is necessary to effectively transfer heat from air forced by a fan into a heat exchanger containing plenum. The heat exchanger, of the heating type, is of the electrical resistance format, and in order to provide maximum heat exchanger life it is important that a uniform flow of forced air pass over the heat exchanger to prevent localized hot or cold spots on the heat exchanger, efficiently transfer the heat from the heat exchanger to the air, and provide a uniformly heated air to the blanket. Also, in order to provide accurate temperatue control, the temperature of the air flowing over the thermal sensor downstream of the heat exchanger must be substantially equivalent to the uniformly heated air supplied to the blanket.
Diffusers for heated air often take the form of louvers or vanes, such as shown in U.S. Pat. Nos. 1,879,152; 2,241,753; 2,699,323 and 4,176,709. However, conventional air diffusers used in conjunction with heat exchangers of the aforementioned type are not suitable for use with concisely related heat exchangers employing a closed plenum, and prior to the advent of the instant invention an efficient and concise air/heat exchanger system using an air diffuser has not been available.